As one of information processing systems, there is a system which communicates between a client terminal and a server. In this information processing system, a processing system in the client terminal (for example, a operating system or a middleware) is an open architecture. As a result, to change of a processing system or to add an application are easy.
With such a development of a processing system becoming the open architecture, it is necessary to protect the processing system from a malicious third party, and to correct a defect of the processing system which is an abnormal state. Accordingly, it becomes necessary for a user to update frequently the processing system or to reinstall. To update the processing system is generally performed in the server and the client terminal (for example, PC (Personal Computer)). At present, also among mobile terminals (mobile communication terminal, portable terminal) such as a mobile phone, a terminal of which a processing system is an open architecture appeared. As for such mobile terminals, there are, for example, Android of Google Inc. and iPhone of Apple Inc. Therefore, in the future, it is expected that, even when the mobile terminal is used as a client terminal, a user needs to update the processing system.
In many cases, after updating the processing system or reinstalling it, it is necessary to restart. Users cannot use the processing system during the restart. For this reason, there is a problem that an application which operates based on the processing system cannot be used either during the restart. In the mobile terminal, it is desired that a user can always use, in particular, basic functions such as a telephone function and an electronic mail function. Therefore, same as the PC or the server, when a need arises for a user to frequently update the processing system in the mobile terminal, it increases that the basic function and so on cannot be used temporarily during the update operation (during restart). Accordingly, there is a concern that a usability of the mobile terminal may decline. Further, as the case when the processing system or the application which operates based on the processing system cannot be used, in addition to the case when the processing system is updated or the case when it is reinstalled mentioned above, for example, there is a case when abnormality occurs within the processing system or a case when a specific environment is reached.
A method to solve such a problem that a function of the client terminal cannot be used temporarily by updating the processing system is disclosed, for example, by Japanese Patent Application Laid-Open No. 2008-210071. In the method, the processing system becomes redundancy (duplicate) in either one of the client terminal or the server.